Sol-gel Method Research Articles

Sol-gel synthesis of LaFeO3 perovskite oxide for distinct ridges detection of level II and III latent fingerprints

Latent fingerprints are considered a primary source of best reference for personal identification in criminal investigations. However, poor resolution, less background hindrance, and sensitivity over fingerprint ridges are often problems in fingerprint development. To address these issues, special care is required by developing new fluorescence materials. As a result, this effort was made to synthesize lanthanum ferrite (LaFeO3) fluorescent nano perovskite oxide by the sol–gel method using glycine as fuel, to detect three (I, II, and III) levels of fingerprints. In addition, the absorption spectrum was recorded in a dispersed medium, and dual peaks at 329 and 406 nm in visible regions were obtained, followed by the photoluminescence spectra that showed a broad peak at 527 nm with chromaticity coordinates. Powder X-ray diffraction confirms the synthesized LaFeO3 orthorhombic phase with a crystallite size of 54 nm, and the morphology of LaFeO3 was found to be highly monodisperse. X-ray photoelectron spectroscopy confirmed that La has + 3 with Fe + 3 oxidation states, and Infrared spectroscopic techniques revealed all functional groups were present uniformly. The powder dusting method was applied on various porous and non-porous surfaces, revealing distinct ridges of fingerprints without background hindrance and with precise sensitivity; this proves LaFeO3 is suitable for forensic science.

Sustainable production of biodiesel from waste cooking oil using magnesium oxide nano catalyst: An optimization study

Biodiesel is rapidly becoming an efficient substitute for fuel and a potentially significant future renewable energy source. In recent years, used cooking oil has been used as a feedstock for biofuel to reduce production costs. Due to its high catalytic activity, low cost, and eco-friendliness, Nano magnesium oxide (MgO) has attracted attention as a catalyst for biodiesel production. Our work presents the preparation of nanomagnesium oxide (MgO) by the sol–gel method, and its characterization. Optimum conditions and the productive combination of waste cooking oil, methanol, and the synthesized nanocatalyst were predicted using response surface methodology. The optimum conditions were methanol to oil ratio of 7:1, temperature of 50 °C and time of 60 min. The expected values for the yield of biodiesel production responses are quite like the actual values, demonstrating the consistency of the models used for establishing a relationship between the independent process variables and the responses. The predicted model's F-value was 9.09 indicating that the model is significant. The model's pure error had a poor correlation, as the "Lack of Fit F-values” 4.16. The quadratic model fits the data well because the R-squared value for the model equation 92%. The expected values for the yield of biodiesel production responses are quite like the actual values, demonstrating the consistency of the models used for establishing a relationship between the independent process variables and the responses. Biodiesel was characterized using gas chromatography–mass spectrometry and Fourier transform infrared spectroscopy.

Detection of riboflavin concentration by sol-gel silica coated dual-peak long period fiber grating sensor

A dual-peak long period fiber grating (DP-LPFG)-based sensor was designed and fabricated for the sensitive detection of riboflavin concentration. LPFGs with a period of 163 μm and a cladding mode of LP0, 12 were inscribed on a standard single-mode silica fiber using a femtosecond laser direct writing technique. Coatings of silica-based materials doped with β-cyclodextrin (β-CD), prepared via the sol-gel method, were applied to the surface of the LPFGs for the detection of riboflavin. To investigate the impact of coating thickness on the sensing sensitivity, sol-gel coatings of different thicknesses were applied to the surface of the LPFG sensor. Experimental findings revealed that the sensor with a thickness of approximately 540 nm sol-gel coatings exhibited superior sensing performance. The detection limit of the prepared DP-LPFG sensor was tested to be 0.08 nM, and it exhibits a response time of less than 3 minutes, along with high sensitivity, excellent repeatability, and selectivity. Thus, this sensor holds significant promise for applications in disease treatment and diagnosis, as well as in ensuring food quality.

Preparation and Photodegradation of TiO2 Thin Films on the Inner Wall of Quartz Tubes.

Titanium dioxide thin films on the inner wall of quartz tubes were prepared in situ by the sol-gel method. Meanwhile, copper and cerium were loaded onto the surface of the titanium dioxide thin films to enhance photocatalytic activity and broaden the range of light absorption. X-ray diffractometer, X-ray photoelectron spectroscopy, scanning electron microscopy, energy dispersive X-ray spectrum, N2 gas adsorption, UV diffuse reflectance spectroscopy, electron paramagnetic resonance, photoluminescene spectroscopy, and so on were used to characterize the structure, morphology, chemical composition, and optical properties of the prepared photocatalyst. Methylene blue (MB) was used as a simulated organic pollutant to study the photocatalytic performance of the photocatalyst, which was a translucent, structurally stable, and reusable high-efficiency photocatalytic catalyst. Under UV lamp irradiation, the MB photodegradation efficiency was 94.5%, which reached 91.2% after multiple cycles.

Carboxymethyl cellulose-coated iron-doped hollow silica carriers with erythrocyte-like structure for improved foliar adhesion and responsive pesticide delivery

The development of nanopestcide carriers with high foliage adhesion remains a challenging task. Erythrocytes are double concave disc structure with thinner center and thicker rim and erythrocyte-like carriers would present enhanced foliar affinity. In this study, we fabricated novel rough-surfaced erythrocyte-like carriers for pesticide delivery. Firstly, erythrocyte-like silica (ES) nanoparticles were prepared by sol-gel method. Subsequently, the ES nanoparticles were further hydrothermal treated to obtain rough-surfaced iron-doped hollow ES (Fe-EHS) nanocarriers. The Fe-EHS nanocarriers could increase contact area and form a topological effect between the pesticide carriers and the micro/nanostructures on plant foliage, effectively enhancing the retention and rain fastness on foliage. Fe-EHS nanocarriers presented a loading capacity of 38.1 % for imidacloprid (IMI). After loading IMI, carboxymethyl cellulose (CMC) was encapsulated to generate nanopesticide delivery system (IMI@Fe-EHS-CMC). The obtained IMI@Fe-EHS-CMC exhibited good foliar adhesion, biosafety, and excellent UV shielding. Additionally, the IMI@Fe-EHS-CMC system possessed pH/cellulase responsive release behavior and could be bidirectionally transported through vascular bundles in tobacco plants. Furthermore, the IMI@Fe-EHS-CMC system showed potent insecticidal activity. This work offers valuable insights for enhancing the effective utilization of pesticides.

Investigation of the Structural, Phase Formation, Optical, Bias-Dependent Dielectric and Visible Region Photocatalytic Degradation Performance of Zn1−xFexO Nanoparticles Prepared Using the Sol–Gel Method

Investigation of the Structural, Phase Formation, Optical, Bias-Dependent Dielectric and Visible Region Photocatalytic Degradation Performance of Zn1−xFexO Nanoparticles Prepared Using the Sol–Gel Method

Synthesis and characterization of the doped/co‐doped SnO2 nanoparticles by the sol–gel method

AbstractTin oxide (SnO2) is one of the important semiconductors used in the application of solar cells because of its chemical–mechanical stability and wide band gap. These properties are very important for the performance development and photoanode optimization of a dye‐sensitized solar cell (DSSC). However, the low conduction band value of SnO2 reduces the photovoltaic efficiency, which limits the application of DSSC. Therefore, the doping strategy was used to increase the sensitivity to the visible light spectrum and change the light absorption properties of SnO2. In this paper, pure SnO2, Ag/SnO2, Pt/SnO2, and Pt/Ag/SnO2 nanoparticles were synthesized at the nanoscale by a simple chemical sol–gel method. To characterize the structure, morphological/chemical properties, optical properties, and surface properties of the synthesized SnO2 nanoparticles, X‐Ray Diffraction (XRD), ultraviolet–visible, Brunauer–Emmett–Teller, Scanning Electron Microscopy (SEM)/Energy Dispersive X‐Ray Spectroscopy (EDX), Transmission Electron Microscopy (TEM), and particle size analysis were respectively used. XRD results showed that the crystal sizes varied between 8.8 and 12.2 nm depending on the doping. Doping processes resulted in reductions in particle sizes. Optical studies resulted in decreases in the band gap with the doping process. The conclusions obtained have shown that Ag doping, and Pt–Ag co‐doping can be promising for use as photoanode materials in semiconductor technology and especially in DSSC applications.

Preparation and Characterization of Black Phosphene/Titanium Dioxide Composite Nanomaterials by Liquid-Stripping and Solution Mixing Method

In this study, black phosphorus (BP) was prepared via the high-energy ball milling method, and two-dimensional (2D) BP was further fabricated using the liquid-phase stripping approach. Nano TiO2 was synthesized via the sol-gel method, and it was combined with black phosphene through N, N-dimethylformamide (DMF) medium by a straightforward solution mixing process to produce BP/ TiO2 composite photocatalyst. Subsequently, spectrophotometric analysis, X-ray diffraction (XRD), and high-resolution transmission electron microscopy (HRTEM) were conducted. The band gap of BP was calculated using the Tauc plot method. The results revealed that the values are 1.06 eV and 1.23 eV, corresponding to the band gap emissions of four-and three-layer BP band gap emission, indicating the successful preparation of few layers of black phosphorus. The HRTEM analysis demonstrated that the BP/ TiO2 composite photocatalyst formed a relatively stable crystalline state.

Investigation of magnetocapacitance and magnetoconductivity in single-phase Y-Type hexaferrite Ba2Co2Fe12O22 nanoparticles

This research paper examines the synthesis and characterization of Y-type hexaferrite Ba2Co2Fe12O22 nanoparticles produced using the sol-gel method. The study explores their structural, magnetic, and electrical properties, confirming the successful synthesis of pure-phase hexaferrites with a hexagonal structure at an annealing temperature of 1150 °C. Morphological analysis reveals changes in nanoparticle diameter based on varying annealing temperatures. The Ba2Co2Fe12O22 nanoparticles display soft ferrimagnetism, achieving a peak saturation magnetization of 52.31 emu/g at 1150 °C, along with notable magnetocrystalline anisotropy and anisotropy field. Investigations on magnetocapacitance and magnetoconductivity under magnetic fields revealed improved performance, with high magnetocapacitance (MC%) and magnetoconductivity (MσAC%) percentages of 24 % and 21 %, respectively. This suggests the potential utility of these nanoparticles in applications such as permanent magnets, magnetic recording media, and spintronic devices.

Photocatalytic degradation of methylene blue in aqueous media using magnesium-substituted copper ferrite as a magnetic catalyst

In this study, copper nanosized ferrites substituted with magnesium ions were synthesized using the sol-gel self-combustion method, with polyethylene glycol (MW 2000) serving as both fuel and chelating agent. Structural properties were investigated using X-ray diffraction. It was confirmed that all samples crystallized as cubic spinels with space group Fd3m. Optical studies showed band gaps increasing from 1.51 eV for CuFe2O4 to 1.62 eV for MgFe2O4, suggesting modifications in electronic structure due to magnesium substitution. Photocatalytic studies revealed that CuFe2O4 exhibited the most efficient degradation of Methylene Blue dye, with near-complete degradation at 160 minutes. Magnesium-substituted samples (x = 0.4 and x = 0.6) also showed significant degradation, though at a slower rate compared to pure CuFe2O4. Photocatalytic performance, particularly in degrading Methylene Blue, was evaluated using various kinetic models such as First- and Second-Order Kinetics, the Langmuir-Hinshelwood model, and the two-parameter Weibull distribution.

Effects of doping of Sm, Y, Ce and La on crystal structure, phase and photocatalytic performance of TiO2 powders prepared by sol-gel method

In the present work, pure and 1 mol% samarium (Sm), yttrium(Y), lanthanum (La), cerium (Ce)-doped titanium dioxide (TiO2) powders were prepared by sol-gel method. Taking Methylene blue (MB) dye as degradation targets the photodegradation performance of the photocatalysts was studied. XRD spectra confirmed that the doping of rare earth elements (RE) could inhibit the transformation of TiO2 from anatase to rutile crystal at high temperature of 800 °C. XPS analyzed the chemical state of the elements in the powder. Characterization such as SEM and TEM found that the doping of the RE elements made the severely agglomerated particles become dispersed and refined, increased the specific surface area, and reduced the optical bandgap. Simulated visible light degradation results of MB showed that the degradation efficiency was significantly improved by doping of the RE elements, and the best efficiency is 88 % for Sm-doped TiO2 powder samples.

Research on cadmium-injected manganese ferrite made through the sol-gel method, focusing on its structure, magnetic properties, electrical conductivity, and electrochemical behavior

Cadmium was integrated into Manganese ferrite (Mn1-xCdxFe2O4) nanofine particles via the sol-gel method for potential sensing uses. The X-ray diffraction (XRD) revealed that the particles contained a cubic spinel structure and FTIR spectroscopy was employed to identify the metal-oxide (MO) stretching, bending and stretching vibrations. The purity of the samples and the surface feature were scrutinized using an energy dispersive X-ray (EDAX) spectrum and scanning electron microscope (SEM). The magnetic properties were examined as ferromagnetic found through a vibrating sample magnetometer (VSM). An LCR meter gives information on dielectric constants (ε’ & ε’’), loss (tanδ) with AC conductivity (σAC), and cyclic-voltammetry was used to evaluate the electrochemical properties, including voltage/current responses (V/I), Nyquist frequency, voltage/current response to SCR, and phase angle as a function of frequency. From the results the magnetic, dielectric, electrochemical behavior and etc., can be interpreted and discussed extensively.

Synthesis, Structure, Photoluminescence, and Optical Properties of (Co/B) Co‐Doped ZnO Nanoparticles

AbstractCo/B co‐doped ZnO nanoparticles, denoted as Zn0.95‐xBxCo0.05O, are synthesized using the sol–gel method to explore the effects of the defects on optical properties. The stoichiometry is adjusted by varying the doping levels (x = 0.00, 0.01, 0.02, 0.03, 0.04, and 0.05). X‐ray diffraction is employed to analyze the structural characteristics of all Co/B co‐doped ZnO nanoparticles, confirming the presence of a hexagonal Wurtzite structure by assessing the c/a ratios. To investigate structural defects, photoluminescence properties are measured using the Fluorescence Spectrophotometer, revealing violet, blue, green, and red emissions. With the doped of boron (B), a shift from green emission to blue emission occurs, indicating a transformation of singly charged oxygen vacancies (VO+) to VZn vacancies. Fourier Transform Infrared (FTIR) spectra (4000–400 cm−1) are acquired using the Perkin Elmer Spectrum Two FTIR‐ATR spectrophotometer. The surface morphology, crystallite size, and nanoparticle shapes are characterized through Transmission Electron Microscope (TEM) analysis. Elemental compositions are determined using Electron Dispersive Spectroscopy (EDAX). The Shimadzu 2600 UV‐Spectrophotometer is used to examine optical characteristics. The samples' energy band gaps are calculated, and the impact of dopant elements on these optical characteristics is examined. Five different models are used to compute the refractive index.

The Effect of the Number of Precursor Spin-Coating on the Properties of Sb<sub>2</sub>(S,Se)<sub>3</sub> Thin Film

Preparing of Sb2S3 precursor by sol gel method and the post selenization is a simple and low-cost method for preparing Sb2(S, Se)3. In the preparation process of this method, the number of spin-coating of Sb2S3 precursor determines the film thickness, structure, and S/Se ratio. In this work, the effects of different spin-coating times (1 to 5) on the structure, optical and electrical properties of the film were studied. The results showed that when the number of spin-coating increased from 1 to 5, the thickness of the film increased from 0.24 μm to 1.17 μm. When spin-coating twice, the strongest diffraction peak of the film changed from (120) to (230); as the spin-coating frequency continued to increase, the film gradually exhibited Sb2S3 characteristics, accompanied by a small amount of Sb2O3 impurities. In addition, excessive spin-coating cycles can cause large voids to appear on the surface of the film. From the UV-visible spectrum, it can be seen that as the thickness of the film increases, the light absorption also gradually improve, and the band gap increases from 1.34 eV to 1.66 eV. The Mott-Schottky test showed that the prepared thin films were all P-type semiconductor. When spin-coated twice, the carrier concentration of the thin film reached 5.8×1015cm-3.

Mg/Ti co-substituted P2-Na0.67Ni0.23Mg0.05Ti0.05Mn0.67O2 cathode with outstanding performance for Na-ion batteries

P2-type layer oxides are one class of cathode materials for Na-ion batteries (SIBs) with the advantages of good rate and cycle performance, but suffer from poor storage stability and relative low capacity, hindering their practical applications. In this study, the Mg/Ti co-substituted P2-type layered oxide Na0.67Ni0.23Mg0.05Ti0.05Mn0.67O2 (NMgTiM) was synthesized via sol–gel method. The initial capacity of NMgTiM reached to 162.2mAh g−1, which is more than twice that of pristine oxides Na0.67Ni0.33Mn0.67O2 (NM), showing an excellent synergistic effect. Long-cycle testing showed that the NMgTiM delivered a high and stable capacity of 165 ∼ 180mAh g−1 at 0.5C before 80 cycles, and remained at 132.6mAh g−1 with a capacity retention of 81.6 % at 100th cycle. The crystal structure of pristine and Mg/Ti substitution samples was confirmed by XRD analysis.

Influence of TiO2-MWCNTs nanohybrid material on the corrosion resistance of epoxy low-zinc coatings

Aiming to improve the corrosion resistance of epoxy low-zinc coatings in marine environments, TiO2-MWCNTs nano-hybridized materials were prepared by sol-gel method in this study, and different contents of reinforcing phases were implanted as to improve the anticorrosive properties of epoxy low-zinc coatings. Characterization of the microscopic morphology, physical phase composition and chemical structure of the TiO2-MWCNTs materials demonstrated that the TiO2 hybridization was successful and the loading of TiO2 improved the dispersion of MWCNTs. To investigate the effect of the additive reinforcing phase on the mechanical and corrosion resistance of the coatings by characterizing the coating microscopic morphology, surface wettability, substrate adhesion, and impedance changes at different immersion times. The above results demonstrated that the epoxy composite coating had lower surface energy and 16 % larger surface contact angle compared with the pure epoxy low-zinc coating; the 0.4 wt% TiO2-MWCNTs/epoxy composite coating had the highest adhesion of 6.52 MPa. The electrochemical test results indicated that the TiO2-MWCNTs/epoxy low-zinc composite coating had the largest self-corrosion potential, the smallest self-corrosion current density of 4.538 μA/cm2, and the largest impedance of 242.3 KΩ/cm2. The addition of TiO2-MWCNTs reinforcing phase significantly extended the barrier protection time of the epoxy low zinc coating and maintained good corrosion resistance throughout the immersion cycle.

Amine-functionalized cellulose-silica composites for the remediation of hexavalent chromium (Cr IV) in contaminated water

Adsorption method for Hexavalent chromium (Cr(VI) removal from domestic and industrial wastewater is widely desirable due to public health concern of the heavy metal. The purpose of this study was to investigate the evaluation of Cr(VI) adsorption using a novel adsorbent: amine-functionalized cellulose-silica composite derived from banana fibers. We employed the in-situ sol–gel method to create cellulose-silica silane functionalized composites, analyzing them through different characterization techniques such as Attenuated total reflectance- Fourier transform infrared spectroscopy (ATR-FTIR), X-ray Diffraction Analysis (XRD), Thermo gravimetric analysis (TGA)/differential thermogravimetric (DTG), Brunauer–Emmett–Teller (BET), Scanning Electron Microscopy (SEM), and Transmission Electron Microscopy (TEM) techniques. ATR-FTIR depicted key organic constituents in raw banana pseudo stem fibers (BF) and the formation of SiO bonds in BCSiO2 composite, and further enhanced by the grafting of N-[3-(trimethoxysilyl)propyl ethylenediamine (DAPTMS) onto the BC-SiO2 surface in BC-SiO2-DAPTMS. XRD and TGA/DTG analyses revealed changes in crystallinity and thermal stability, while BET analysis showcased altered surface area and pore characteristics in BC-SiO2-DAPTMS (2 %). SEM and TEM imaging provided visual evidence of structural modifications and improved dispersion in BC-SiO2-DAPTMS composites. The impact of composite weight, contact time, and pH on Cr(VI) removal rates was examined, revealing optimal performance at slightly acidic pH 4 value (80.7 %) and enhanced efficiency with increased contact time of 65 min (86.66 %), composite weight of 1 g (82.62 %), and initial concentration was for 0.8 mg/l (80 %). The kinetics and isotherms analyzed using pseudo second order (PSO) and pseudo first order (PFO) models, highlight the composite’s efficiency. The Freundlich model was found to better fit the adsorption isotherm data, while the PSO model described the kinetics more accurately. These insights contribute to optimizing the BC-SiO2-DAPTMS (2 %) composite for efficient Cr(VI) ion removal in water treatment applications.

Effects of electrical and mechanical properties of Ba0.92Ca0.08Zr0.05Ti0.95O3 ceramics with lanthanum dopants

Element doping is one of the important approaches to improve the performance of lead-free piezoelectric ceramics. In this study, Ba0·92Ca0·08Zr0·05Ti0·95O3-xLa (BCZT-xLa) piezoelectric ceramics were prepared by sol–gel method. The effects of La3+ contents on the phase structure, mechanical properties, and electrical properties of BCZT-xLa ceramics were investigated. Results showed that La3+ could affect the properties of ceramics by adjusting the concentration of oxygen vacancies and microstructure. When the La3+ contents were 0.008, the ceramics showed the best performance (the maximum permittivity was 8736.27, the remnant polarisation was 9.69 μC/cm2 and the coercive field was 3.44 kV/cm). The influences of Vickers hardness on ceramics were investigated using various La3+ contents. The lattice energy and oxygen vacancies were the main factors for the change in Vickers hardness. With an increment of x, the Vickers hardness values decreased from 6.271 GPa to 1.438 GPa. This study could provide a reference for BCZT piezoelectric ceramics doped with rare earth elements.

Thermal Stability Improvement of Cu-Based Catalyst by Hydrophobic Modification in Methanol Synthesis

Water can cause the growth and oxidation of Cu nanoparticles on the surface of Cu-based catalysts, leading to their deactivation. However, during methanol synthesis process from syngas on Cu-based catalysts, water is inevitably produced as a by-product due to the presence of CO2. Therefore, enhancing the stability of Cu-based catalysts during the reaction, particularly in the presence of water, is crucial. In this study, Cu/ZnO/Al2O3 was first subjected to wet etching and then hydrophobically modified using the sol–gel method with methyltrimethoxysilane (MTMS) and the grafting method with 1H,1H,2H,2H-perfluoroalkyltriethoxysilanes (PFOTES) as modifiers. These modifications aimed to mitigate the impact of water on the catalyst and improve its stability. After modification, the catalysts exhibited excellent hydrophobicity and enhanced catalytic activity in the methanol synthesis process. The surface physical properties, composition, and thermal stability of the catalysts before and after hydrophobic modification were characterized by SEM, FT-IR, BET, XRD and TGA. Additionally, molecular dynamics simulations were employed to compare the diffusion behavior of water molecules on the catalyst surfaces before and after hydrophobic modification. The results indicated that the modified catalyst surface formed a micro/nano structure composed of nanosheets and nanosheet clusters, while the hydrophobic modification did not alter the structure of the catalyst. According to the results of simulations, the hydrophobic layers on the modified catalysts were able to expel water quickly from the surfaces and reduce the relative concentration of water molecules at the active sites, thereby improving the stability of the catalyst. Notably, the thermal stability and hydrophobicity of the PFOTES-modified catalyst were superior to those of the MTMS-modified catalyst, resulting in a more significant enhancement in catalyst stability, which aligned with the experimental results.

Comprehensive analysis of Nd0.5Ba0.5CoO3 cobaltite: Unveiling electrical, optical and magnetic characteristics for optoelectronic applications

In this study, we successfully synthesized the perovskite cobaltite Nd0.5Ba0.5CoO3 (NBCO) using the sol-gel method and thoroughly characterized its optical and magnetic properties. Optical measurements, using UV absorption, the Tauc model, and diffuse reflectance spectroscopy (DRS), revealed multiple direct bandgap energies, with the most significant values being 5.23 eV (Tauc method), 5.1 eV (DRS), and 4.9 eV (reflectance). The high bandgap energies highlight NBCO's suitability for UV and optoelectronic applications. The refractive index varied between 2.48 and 3.55, while the Urbach energy was measured at 2.32 eV, indicating a moderate level of localized disorder. Magnetic characterization demonstrated a ferromagnetic-to-paramagnetic transition at 125 K, with strong molecular field effects influencing the exchange interactions. The dielectric analysis revealed an exceptionally low loss factor (tan δ ≈ 0.0012), underscoring NBCO's potential for efficient energy storage and electronic applications. These results show that NBCO offers a unique combination of high optical bandgaps, strong magnetic properties, and low dielectric loss, making it a promising candidate for advanced optoelectronic and magnetic devices.